A horizontal shift sensing apparatus is mounted on and moved along with an object to sense and measure any difference in angle of inclination of the object when the object moves. The object may be a wheelchair, rocker, aircraft, and any vehicle and the apparatus helps horizontal adjustment of such objects with minimized manual manipulation.
FIGS. 1 and 2 are exploded and assembled perspective views, respectively, of a conventional horizontal shift sensing apparatus. As shown, the conventional apparatus mainly includes close-up upper cover 1 and lower cover 11 that have inner seats 10 and 4, respectively. The inner seat 4 is formed on its upper edges with cuts 41. Two rocking arms 3 are separately rested across the inner seat 4 with reduced necks 32 provided at two ends thereof seated in the cuts 41, so that the rocking arms 3 intersect without touching each other. The rocking arm 3 each further has a recess 33 provided at one end outside the reduced neck 32 for a V-shaped spring 42 to engage thereinto, so that the V-shaped springs 42 always restore the biased rocking arms 3 to an original position. A toothed quarter sector 34 is provided at the other end of each rocking arm 3 opposite to the recess 33. A wheel 43 is mounted onto the inner seat 4 at one side of each rocking arm 3. Each wheel 43 has an optical wheel 431 associated therewith and a gear 432 sideward projected from a center of the wheel 43. The toothed quarter sector 34 meshes with the gear 432 and therefore rotates the wheel 43 and accordingly the optical wheel 431. To allow the rocking arms 3 to sway sideward or forward and backward, the rocking arms 3 have an arched middle portion provided with a through hole 31. A movable ball 23 having a top hole 231 and a T-shaped bottom member 232 is associated with the rocking arms 3 such that the T-shaped bottom member 232 is located below the through holes 31 of the two rocking arms 3. A rocker 22 is connected to the movable ball 23 by inserting a lower end thereof into the top hole 231 of the ball 23. A circuit board 2 provided with recesses 20 is disposed around the wheels 43, so that outer peripheries of the wheels 43 are located in the recesses 20. With these arrangements, when the rocker 22 sways, it brings the rocking arms 3 to sway. At this point, the toothed quarter sectors 34 on the rocking arms 3 rotate the wheels 43. The optical wheels 431 on the rotating wheels 43 move in the recesses 20 of the circuit board 2. Such movement of the optical wheels 431 is sensed by phototransistors 21 mounted on the circuit board 2 at two sides of the recesses 20 and converted into a value representing a distance of displacement of the rocker 22.
In the above-described conventional horizontal shift sensing apparatus, the rocker 22 is utilized to shift an object. However, the rocker 22 itself can not be actively controlled. Moreover, the wheels 43 are the only means to indicate the shift of the object and do not provide accurate result. And, since the rocking arms 3 are provided with only one toothed quarter sector 34 each, the quarter sectors 34 tend to disengage from the gears 432 and cause disorder of the wheels 43 when the rocking arms 3 are biased too much by the rocker 22. The conventional horizontal shift sensing apparatus can therefore be used in limited shifting range. In brief, the whole apparatus needs manual manipulation to drive other electronic elements in the apparatus, including resistances, phototransistors, etc. and has limited effects.
It is therefore desirable to develop an improved horizontal shift sensing apparatus to eliminate the drawbacks existing in the conventional apparatus.